TCP/IP Model

The TCP/IP model is a conceptual framework that standardizes the functions of a telecommunication or computing system in terms of abstraction layers. It's the core protocol suite of the internet. Understanding these layers is fundamental for any cybersecurity professional because different attacks target different layers. The model is typically divided into four layers. 1. The Application Layer is the top layer, where user-facing applications like web browsers (HTTP/HTTPS), email clients (SMTP), and file transfer programs (FTP) operate. Security concerns at this layer include application-level attacks like SQL injection and Cross-Site Scripting (XSS). 2. The Transport Layer is responsible for end-to-end communication and error-free delivery of data. The two primary protocols here are TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). TCP is connection-oriented and reliable, ensuring all data arrives in the correct order, making it suitable for web browsing and email. UDP is connectionless and faster but less reliable, used for services like video streaming or online gaming where speed is more critical than perfect data integrity. Attacks at this layer include SYN floods and port scanning. 3. The Internet Layer (or Network Layer) is responsible for logical addressing and routing of packets across networks. The main protocol here is IP (Internet Protocol), which assigns unique IP addresses to devices. This layer is where packets are routed from a source to a destination. Attacks include IP spoofing and packet sniffing. 4. The Link Layer (or Network Interface Layer) is the lowest layer, responsible for the physical transmission of data over the media (e.g., Ethernet, Wi-Fi). It deals with MAC addresses and the physical hardware. Attacks at this layer include MAC spoofing and ARP poisoning.